br_forward.c 5.9 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1
2
3
4
5
6
7
8
9
10
11
12
13
/*
 *	Forwarding decision
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

14
#include <linux/err.h>
15
#include <linux/slab.h>
Linus Torvalds's avatar
Linus Torvalds committed
16
17
18
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
19
#include <linux/if_vlan.h>
Linus Torvalds's avatar
Linus Torvalds committed
20
21
22
#include <linux/netfilter_bridge.h>
#include "br_private.h"

23
24
static int deliver_clone(const struct net_bridge_port *prev,
			 struct sk_buff *skb,
25
26
27
			 void (*__packet_hook)(const struct net_bridge_port *p,
					       struct sk_buff *skb));

28
/* Don't forward packets to originating port or forwarding diasabled */
29
static inline int should_deliver(const struct net_bridge_port *p,
Linus Torvalds's avatar
Linus Torvalds committed
30
31
				 const struct sk_buff *skb)
{
32
33
	return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
		p->state == BR_STATE_FORWARDING);
Linus Torvalds's avatar
Linus Torvalds committed
34
35
}

36
37
38
39
40
static inline unsigned packet_length(const struct sk_buff *skb)
{
	return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
}

Linus Torvalds's avatar
Linus Torvalds committed
41
42
int br_dev_queue_push_xmit(struct sk_buff *skb)
{
43
	/* drop mtu oversized packets except gso */
Herbert Xu's avatar
Herbert Xu committed
44
	if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
Linus Torvalds's avatar
Linus Torvalds committed
45
46
47
		kfree_skb(skb);
	else {
		/* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
48
49
		if (nf_bridge_maybe_copy_header(skb))
			kfree_skb(skb);
50
		else {
51
			skb_push(skb, ETH_HLEN);
Linus Torvalds's avatar
Linus Torvalds committed
52

53
54
			dev_queue_xmit(skb);
		}
Linus Torvalds's avatar
Linus Torvalds committed
55
56
57
58
59
60
61
	}

	return 0;
}

int br_forward_finish(struct sk_buff *skb)
{
62
63
	return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
		       br_dev_queue_push_xmit);
Linus Torvalds's avatar
Linus Torvalds committed
64
65
66
67
68
69
70
71
72
73
74
75
76
77

}

static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
	skb->dev = to->dev;
	NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
			br_forward_finish);
}

static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
{
	struct net_device *indev;

Herbert Xu's avatar
Herbert Xu committed
78
79
80
81
82
	if (skb_warn_if_lro(skb)) {
		kfree_skb(skb);
		return;
	}

Linus Torvalds's avatar
Linus Torvalds committed
83
84
	indev = skb->dev;
	skb->dev = to->dev;
85
	skb_forward_csum(skb);
Linus Torvalds's avatar
Linus Torvalds committed
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102

	NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
			br_forward_finish);
}

/* called with rcu_read_lock */
void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
{
	if (should_deliver(to, skb)) {
		__br_deliver(to, skb);
		return;
	}

	kfree_skb(skb);
}

/* called with rcu_read_lock */
103
void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
Linus Torvalds's avatar
Linus Torvalds committed
104
{
Herbert Xu's avatar
Herbert Xu committed
105
	if (should_deliver(to, skb)) {
106
107
108
109
		if (skb0)
			deliver_clone(to, skb, __br_forward);
		else
			__br_forward(to, skb);
Linus Torvalds's avatar
Linus Torvalds committed
110
111
112
		return;
	}

113
114
	if (!skb0)
		kfree_skb(skb);
Linus Torvalds's avatar
Linus Torvalds committed
115
116
}

117
118
static int deliver_clone(const struct net_bridge_port *prev,
			 struct sk_buff *skb,
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
			 void (*__packet_hook)(const struct net_bridge_port *p,
					       struct sk_buff *skb))
{
	skb = skb_clone(skb, GFP_ATOMIC);
	if (!skb) {
		struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;

		dev->stats.tx_dropped++;
		return -ENOMEM;
	}

	__packet_hook(prev, skb);
	return 0;
}

static struct net_bridge_port *maybe_deliver(
	struct net_bridge_port *prev, struct net_bridge_port *p,
	struct sk_buff *skb,
	void (*__packet_hook)(const struct net_bridge_port *p,
			      struct sk_buff *skb))
{
	int err;

	if (!should_deliver(p, skb))
		return prev;

	if (!prev)
		goto out;

	err = deliver_clone(prev, skb, __packet_hook);
	if (err)
		return ERR_PTR(err);

out:
	return p;
}

Linus Torvalds's avatar
Linus Torvalds committed
156
/* called under bridge lock */
157
static void br_flood(struct net_bridge *br, struct sk_buff *skb,
158
159
160
		     struct sk_buff *skb0,
		     void (*__packet_hook)(const struct net_bridge_port *p,
					   struct sk_buff *skb))
Linus Torvalds's avatar
Linus Torvalds committed
161
162
163
164
165
166
167
{
	struct net_bridge_port *p;
	struct net_bridge_port *prev;

	prev = NULL;

	list_for_each_entry_rcu(p, &br->port_list, list) {
168
169
170
		prev = maybe_deliver(prev, p, skb, __packet_hook);
		if (IS_ERR(prev))
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
171
172
	}

173
174
175
	if (!prev)
		goto out;

176
177
178
179
	if (skb0)
		deliver_clone(prev, skb, __packet_hook);
	else
		__packet_hook(prev, skb);
180
	return;
Linus Torvalds's avatar
Linus Torvalds committed
181

182
183
184
out:
	if (!skb0)
		kfree_skb(skb);
Linus Torvalds's avatar
Linus Torvalds committed
185
186
187
188
}


/* called with rcu_read_lock */
189
void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
Linus Torvalds's avatar
Linus Torvalds committed
190
{
191
	br_flood(br, skb, NULL, __br_deliver);
Linus Torvalds's avatar
Linus Torvalds committed
192
193
194
}

/* called under bridge lock */
195
196
void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
		      struct sk_buff *skb2)
Linus Torvalds's avatar
Linus Torvalds committed
197
{
198
	br_flood(br, skb, skb2, __br_forward);
Linus Torvalds's avatar
Linus Torvalds committed
199
}
200
201
202
203
204
205
206
207
208
209
210

#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
/* called with rcu_read_lock */
static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
			       struct sk_buff *skb, struct sk_buff *skb0,
			       void (*__packet_hook)(
					const struct net_bridge_port *p,
					struct sk_buff *skb))
{
	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
	struct net_bridge *br = netdev_priv(dev);
211
	struct net_bridge_port *prev = NULL;
212
213
214
	struct net_bridge_port_group *p;
	struct hlist_node *rp;

stephen hemminger's avatar
stephen hemminger committed
215
	rp = rcu_dereference(br->router_list.first);
216
	p = mdst ? rcu_dereference(mdst->ports) : NULL;
217
	while (p || rp) {
218
219
		struct net_bridge_port *port, *lport, *rport;

220
221
222
223
224
225
226
227
228
229
230
231
		lport = p ? p->port : NULL;
		rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
			     NULL;

		port = (unsigned long)lport > (unsigned long)rport ?
		       lport : rport;

		prev = maybe_deliver(prev, port, skb, __packet_hook);
		if (IS_ERR(prev))
			goto out;

		if ((unsigned long)lport >= (unsigned long)port)
232
			p = rcu_dereference(p->next);
233
		if ((unsigned long)rport >= (unsigned long)port)
stephen hemminger's avatar
stephen hemminger committed
234
			rp = rcu_dereference(rp->next);
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
	}

	if (!prev)
		goto out;

	if (skb0)
		deliver_clone(prev, skb, __packet_hook);
	else
		__packet_hook(prev, skb);
	return;

out:
	if (!skb0)
		kfree_skb(skb);
}

/* called with rcu_read_lock */
void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
			  struct sk_buff *skb)
{
	br_multicast_flood(mdst, skb, NULL, __br_deliver);
}

/* called with rcu_read_lock */
void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
			  struct sk_buff *skb, struct sk_buff *skb2)
{
	br_multicast_flood(mdst, skb, skb2, __br_forward);
}
#endif